[GitHub] yanghua commented on a change in pull request #6432: [FLINK-9970] [table] Add ASCII/CHR function for table/sql API

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yanghua commented on a change in pull request #6432: [FLINK-9970] [table] Add ASCII/CHR function for table/sql API
URL: https://github.com/apache/flink/pull/6432#discussion_r206741741
 
 

 ##########
 File path: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/codegen/calls/FunctionGenerator.scala
 ##########
 @@ -146,12 +146,25 @@ object FunctionGenerator {
     STRING_TYPE_INFO,
     BuiltInMethod.OVERLAY.method)
 
+  addSqlFunctionMethod(
+    ASCII,
+    Seq(STRING_TYPE_INFO),
+    STRING_TYPE_INFO,
 
 Review comment:
   @suez1224 thanks for your reminder. You are right, In the scenario you mentioned, it throws an exception. I found that we don't need to check if the input of the function is null. It seems that the Flink framework has been processed by default. All the input is null and will return null (man can not interfere). Then we only need to deal with "", in this case, the ASCII code is 0. So, I directly changed the return value of this method to the Int type. 
   
   cc @hequn8128 : 
   
   It seems that we don't need to consider the case where the input is null. Once the input of the function is null, this function will not be called at all. I debugged it through the test class. It looks like this, you can confirm it.

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